The primary goal of the Mass Spectrometry Resource (MSR) is to provide comprehensive mass spectral and, in the near future, biophysical analyses to investigate within the YCC. The instrumentation required to meet this goal is invariably expensive and requires considerable expertise to operate and to properly interpret the resulting data. The Resource is equipped with a VG-ZAB-SE high resolution, high mass range mass spectrometer equipped with EI and FAB (35 kV Cesium ion) ion sources. The instrument is used to provide low and high resolution mass spectral analyses. The Resource has a Micro-mass Quattro model triple quadrupole instrument equipped with an electrospray ion source manufactured by Analytica, Inc(Branford, CT). This ion source also contains a nanoflow probe. Samples can be introduced by either direct infusion or by HPLC. The Resource is also affiliated with the W.M. Keck Biotechnology Resource in which are housed a Finnegan LCQ and a Micro-mass TofSpec MALDI mass spectrometers ensuring that a wide variety of mass spectral instrumentation can be applied to any sample. The Resource welcomes inquires on the applicability of mass spectrometry to a particular bioanalytical problem. The operation of the MSR is supported by users fees, the Cancer Center Support Grant and the YCC. Questions can be addressed to Walter McMurray at 203-785-6169 or by e-mail at walter.mcmurray@yale.edu.